Re: [PATCH] x86/entry/64: Remove %ebx handling from error_entry/exit

From: Greg KH <gregkh@linuxfoundation.org>
To: Sarah Newman <srn@prgmr.com>
Cc: Juergen Gross <jgross@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Brian Gerst <brgerst@gmail.com>,
	x86@kernel.org, stable@vger.kernel.org, "Durand Wesolowski,
	Jimmy" <jdw@amazon.de>, Borislav Petkov <bp@alien8.de>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	xen-devel@lists.xenproject.org,
	Thomas Gleixner <tglx@linutronix.de>,
	David Woodhouse <dwmw2@infradead.org>,
	Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH] x86/entry/64: Remove %ebx handling from error_entry/exit
Date: Thu, 16 Aug 2018 17:19:46 +0200	[thread overview]
Message-ID: <20180816151946.GH10648__29667.4958816313$1534432731$gmane$org@kroah.com> (raw)
In-Reply-To: <1f15d219-46fd-fc21-84d5-877a7af4c87e@prgmr.com>

On Fri, Aug 10, 2018 at 12:23:45AM -0700, Sarah Newman wrote:
> On 08/09/2018 05:41 AM, David Woodhouse wrote:
> > On Wed, 2018-08-08 at 10:35 -0700, Sarah Newman wrote:
> >> commit b3681dd548d06deb2e1573890829dff4b15abf46 upstream.
> >>
> >> This version applies to v4.9.
> > 
> > I think you can kill the 'xorl %ebx,%ebx' from error_entry too but yes,
> > this does want to go to 4.9 and earlier because the 'Fixes:' tag is a
> > bit of a lie — the problem existed before that, at least in theory.
> 
> The commit 2140a9942 "x86/entry/64: Relax pvops stub clobber
> specifications" was what removed the "movl %ebx, %eax" line later on
> originally, but it was the commit 3ac6d8c787b8 that removed the
> 'xorl %ebx,%ebx'. So these weren't matched.
> 
> I don't know if it's a concern, but if someone had gone to the effort of
> backporting the original commit 3ac6d8c787b83, adding the removal of
> 'xorl %ebx,%ebx' to this patch would create merge conflicts.
> For that reason and given the line is harmless, should it be left in?

I need some kind of agreement here for me to know what to do with this
patch...  {hint}

thanks,

greg k-h

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